Have you ruled out the marriage between Elizabeth Milne and William Ewan in Tarves in 1860?
I think this is the family at Throopmuir, Methlick:
1861
William Ewen, head, 32, farmer, Methlick
Elizabeth Ewen, wife, 24, Tarves
Edward Ewen, brother, 20, Methlick
Susan Ewen, sister, 18, Methlick
Ellen Balck, niece, 2, Tarves
1871
William Ewan, head, 42, farmer, Methlick
Elizabeth Ewan, wife, 34, Tarves
Janet Ewan, daughter, 9, Methlick
Alexander Ewan, son, 7, Methlick
William Ewan, son, 5, Methlck
Edward Ewan, son, 3, Methlick
Elizabeth Ewan, daughter, 1, Methlick
Alicia A Ewan, daughter, 1m, Methlick
Helen Black, step daughter, 12, Tarves
Alicia A Ewan, mother, 66, Methlick
Jane Ewan, sister, 31, Methlick
Edward Ewan, brother, 29, Methlick
Isabella Ewan, sister, 23, Methlick
William Cockburn, nephew, 17, Methlick
James Mitchell, nephew, 14, Methlick
1881
William Ewan, head, 52, farmer, Methlick
Elizabeth Ewan, wife, 44, Tarves
Janet Ewan, daughter, 19, Methlick
William Ewan, son, 15, Methlck
Edward Ewan, son, 13, Methlick
James Ewan, son, 5, Methlick
Sarah Ewan, daughter, 3, Methlick
Edward Ewan, brother, 40, Methlick
William and Elizabeth disappear in 1891:
1891
Alexander Ewan, head, 29, farmer, Methlick
Janet Ewan, sister, 29, Methlick
Edward Ewan, brother, 23, Methlick
James Ewan, brother, 16, Methlick
Sarah Ewan, sister, 13, Methlick
Cuthbert Ewan, brother, 9, Methlick
Edward Ewan, uncle, 49, Methlick
William Murray, visitor, 32, Fyvie
There's a death in Methlick in 1889 of an Elizabeth Milne or Ewan, age 53; and a death in 1884 for William Ewen, age 54.
Ruth